Road camber, or cross slope, is a slope of a road perpendicular to the road centerline. The road camber is commonly 1-2%, with the road surface angling slightly downwardly from the crown, or high point, at the centerline of the road to a low point at the edges of the road (e.g., curb, shoulder/median, etc.). Road camber is provided, in part, to facilitate drainage of rainwater, to enhance contact between vehicle wheels and the road and to maintain the strength and durability of the surface concrete and sub-grade soil, which can be harmed by water infiltration.
In some examples, the road camber may be parabolic, straight line, or a combination of straight line and parabolic. The road camber is generally between about 1-3% for straight segments of roadway, but increases to higher values (e.g., 5-10%) for curves (e.g., about 10% for sharp, super-elevated curves to account for centrifugal forces acting on the vehicle relative to the radius of the curve and intended speed limited for vehicles traversing the curve).
Despite the benefits of road camber, the road camber adversely impacts steering and biases steering away from the center of the road. To maintain forward movement of the vehicle in a straight line, the driver is often required to apply a slight torque to the steering wheel to compensate for the tendency of the vehicle to pull in the direction of a low point at an edge of the road.
Driver compensation for road camber may vary in perceptivity and degree based on factors including, but not limited to, degree of road camber, vehicle type, vehicle loading, wheel type, wheel condition, vehicle camber, suspension alignment, and weather (e.g., crosswinds, etc.). In general, tracking of the vehicle off center due to road camber is undesirable and sometimes tiring to the driver, who must consistently input torque to the steering wheel ensure forward movement of the vehicle in a straight line.